Epilepsy and Multiple Subpial Transection (MST)
What Is Multiple Subpial Transection?
Sometimes brain seizures begin in a vital area of the brain -- for example, in areas that control movement, feeling, language, or memory. When this is the case, a relatively new epilepsy treatment called multiple subpial transection (MST) may be an option. MST stops the seizure impulses by cutting nerve fibers in the outer layers of the brain (gray matter), sparing the vital functions concentrated in the deeper layers of brain tissue (white matter).
Who Is a Candidate for Multiple Subpial Transection?
Most people with epilepsy can control their seizures with medication. However, about 20% of people with epilepsy do not improve with drugs. In some cases, surgery to remove the part of the brain causing the seizures may be recommended.
MST may be an option for people who do not respond to medication and whose seizures begin in areas of the brain that cannot be safely removed. In addition, there must be a reasonable chance that the person will benefit from surgery. MST may be done alone or with the removal of a section of brain tissue (resection). MST also may be used as a treatment for children with Landau-Kleffner syndrome (LKS), a rare childhood brain disorder which causes seizures and affects the parts of the brain that control speech and comprehension.
What Happens Before Multiple Subpial Transection?
Candidates for MST undergo an extensive pre-surgery evaluation -- including seizure monitoring, electroencephalography (EEG), magnetic resonance imaging (MRI), and positron emission tomography (PET). These tests help to pinpoint the area in the brain where the seizures occur and determine if surgery is feasible.
Another test to assess electrical activity in the brain is EEG-video monitoring, in which video cameras are used to record seizures as they occur, while the EEG monitors the brain's activity. In some cases, invasive monitoring -- in which electrodes are placed inside the skull over a specific area of the brain -- is also used to further identify the tissue responsible for seizures.